Field of the Invention
The present invention relates to a control device for a mobile robot, such as a legged mobile robot.
Description of the Related Art
Hitherto, there has generally been known a mobile robot provided with movable links (leg links, arm links and the like) connected to a base body through the intermediary of joints, such as a legged mobile robot described in Japanese Patent No. 3813102 (hereinafter referred to as “Patent Document 1”).
In this type of mobile robot, the displacement amount of each joint is usually controlled through the intermediary of a joint actuator, which is constituted of an electric motor or the like, according to a motion command prepared to enable the mobile robot to perform a desired motion in an expected environment.
When operating a mobile robot in a variety of environments, especially in a state in which the motion of the mobile robot has been brought to a halt (e.g. a standby mode for waiting for a motion instruction), a situation in which a load on a particular joint of the mobile robot remains steadily high tends to occur.
For example, in a motion halt mode of a mobile robot engaged in work on an irregular ground, if the shape of the ground surface area with which a leg link of the mobile robot is in contact is disturbed from the original shape thereof or the shape of the ground surface area is unexpected, then the entire attitude of the mobile robot inconveniently deviates steadily from an initially expected attitude. This causes the load on a particular joint to remain steadily high in some cases.
If the situation in which the load on any particular joint of the mobile robot undesirably remains steadily high takes place, then the amount of energy consumed by the joint actuator for driving that particular joint cumulatively increases and the temperature of the joint actuator excessively increases, possibly leading to deteriorated performance of the joint actuator or damage thereto. This may prevent normal motion control of the mobile robot.